Electric resistance material



Patented Nov. 5, 1929 UNITED STATES PATENT, OFFICE TORRENCE A. SWARTZAND WILMER 1P. UHLER, OF TOTTENVILLE, NEW YORK ELECTRIC RESISTANCEMATERIAL No Drawing.

Our invention relates particularly to a composition of matter which/maybe formed to provide electrical resistajfi e devices having extremelhigh resistive qualities.

5 It is wellnown that in certain electrical devices, such as areemployed in wireless apparatus and other highly sensitive instruments,it is necessary to employ resistance of extremely high value, and thatresistance materials, as heretofore produced, lack the desired tensileand transverse strength and therefore have their limitations forinstallation. Furthermore, in resistance devices employing carbon andgraphite coated surfaces,

it is diflicult to either secure or maintain uniformity and permanenceof resistance value.

The principal objects of our invention are to provide an electricalresistance material that will not only afford the infinitely highresistive qualities required, but that will have the tensile andtransverse strength desired, and that will maintain its uniformity andpermanence.

Other objects of our invention are to provide an electric resistancematerial in which the electrical conducting medium may be so varied asto afford an extremely wide range of conductivity and that may bereadily moulded or otherwise formed into any desired shape or drawn intowire if desired, and

which may be flexed and connected in any desired manner.

The form of our invention as hereinafter described comprehends anelectric resistance material formed of a composition of mattercomprising rubber, sulphur and an inert substance serving as a filler,and finely divided particles of electrical conducting material uniformlyembodied therein.

Ourinvention also includes all of the various novel features ofproduction and embodiment as hereinafter more definitely specified.

We have found that a resistance material having extremely highelectrical resistive 4 qualities, combined with the desired featuresApplication filed September 24, 1928. Serial No. 664,575.

inert substance such as blanc fixe or barium sulphate (BaSo) havingembodied therein carbon, preferably in the form of" lamp-black,gas-black, powdered graphite or other suitable finely divided electricalconducting materials, and that these combined substances may beconveniently mixed by the use of rubber mixing rollers in a well-knownmanner.

We have also found that desirable results may be attained by forming thecomposition of forty (40%) per cent rubber, twenty (20%) per centsulphur, fifteen (15%) per cerit-thirty-five (35%) per cent lamp-black,and twenty-five (25%) per cent-five (5%) per cent blanc fixe. It is tobe understood, however, that the proportions herein set forth may bewidely varied to adapt the resulting resistance material to varyingconditions that may be encountered.

\ The composition thus described may be conveniently moulded intosuitable form and vulcanized, preferably to form vulcanite, and may beprepared for use in a variety of forms, such as plates, discs, bars,rods or Wire that may be conveniently adapted to any conditionsordinarily found in commercial devices.

Our invention is advantageous in that it 7 provides a non-fragileresistance material having an infinitely high resistance value. andconsequently can be adapted to conditions not heretofore possible.

We do not desire to limit our invention to 0 the specific materials andtheir proportions herein set forth, as it is obvious that variousmodifications may be made therein without departing from the spirit andscope of the invention as defined in the appended claims.

Having thus described our invention, we claim I 1. An electricalresistance material comprising a vulcanized composition consisting ofrubber, sulphur, barium sulfate and finely divided particles of carbon,the relative rosortions of said barium sulfate and car on etermining thespecific resistivity of the material.

2. An electrical resistance material comprising a coherent vulcanizedcomposition of approximately 40% of rubber, 20% of sulphur, 15 to 35% oflamp black, and 25 to 5% of barium sulfate.

In witness whereof, we have hereunto set our hands the 20th day ofSeptember, A. D., 1923, and the 20th day of September, A. D.,

1923 respectively. TORRENCE A. SWARTZ.

WILMER P. UHLER.

